A number of patents, both U.S. and foreign, disclose air mattresses or cushions comprised of sets of cells which are alternately inflated and deflated to support a patient first on one group of air cells and then the other group. Those patents include the following U.S. Pat Nos. 1,772,310, 2,245,909, 2,998,817, 3,390,674, 3,467,081, 3,587,568, 3,653,083, 4,068,334, 4,175,297, 4,193,149, 4,197,837, 4,225,989, 4,347,633, 4,391,009, and 4,472,847, and the following foreign patents: G.B. 959,103, Australia 401,767, and German 24 46 935, 29 19 438 and 28 07 038. None of the devices disclosed in those patents rolls or alternately moves the patient supported thereon to further distribute the patient's body weight over additional air cushions or cells or to alternately relieve the pressure under portions of the patient's body.
There are also a number of patents which disclose an inflatable device other than an air mattress or cushion but which involve alternately supplying air to a set of cells and then to another set of cells. Those patents include U.S. Pat. Nos. 1,147,560, 3,595,223, and 3,867,732, and G.B. patent 1,405,333. Of those patents, only the British patent discloses the movement of the body with changes in air pressure in the cells of the device. None of those references disclose an apparatus which is adaptable for use in a low air loss patient support system.
British Patent No. 946,831 discloses an air mattress having inflatable elongated sacs which are placed side-by-side and which are in fluid communication with each other. A valve is provided in the conduit connecting the insides of the two sacs. Air is supplied to both sacs in an amount sufficient to support the patient, thereby raising the patient off the bed or other surface on which the air mattress rests. Any imbalance of the weight distribution of the patient causes the air to be driven from one sac to the other, allowing the patient to turn toward the direction of the now deflated sac. An automatic changeover valve, the details of which are not shown, is said to then inflate the deflated sac while deflating the sac which was originally inflated, thereby rocking the patient in the other direction.
The device disclosed in that patent is limited in its ability to prevent bed sores because when the patient rocks onto the deflated sac, there may be insufficient air to support the patient up off the bed or other surface on which the air mattress rests, resulting in pressure being exerted against the patient's skin which is essentially the same as the pressure that would have been exerted by the board or other surface without the air mattress. Even if there were enough air left in the deflated sac to support the patient, if the air mattress were constructed in a low air loss configuration, the air remaining in the sac would be slowly lost from the sac until the patient rested directly on the bed or other surface with the same result. Finally, that device is not adaptable for use on a bed having hinged sections corresponding to the parts of the patient's body lying on the bed so that the angle of inclination of the various sections of the bed can be adjusted for the patient's comfort or for therapeutic reasons.
The present invention is characterized by a number of advantages over the prior art devices, including the ability to maintain air pressure, the ability to quickly and easily replace one or more of the air sacs while the low air loss bed is in operation, and the ease of adjustment of the air pressure in the air sacs.
It is, therefore, an object of the present invention to provide a low air loss, water vapor permeable air sac which is comprised of a substantially rectangular enclosure constructed of a water vapor permeable material, means for connecting the inside of the enclosure with a source of gas for inflating the enclosure, means for releasably securing the enclosure to a low air loss bed, integral means for moving a patient resting on the top surface of the rectangular enclosure towards the end thereof when the enclosure is inflated, and integral means at the end of the rectangular enclosure toward which the patient is moved for retaining the patient on the top surface of the enclosure.
Another object of the present invention is to provide an air sac with a single opening which can be quickly and easily detached from an air bed to allow the easy replacement of the air sac, even while the bed is in operation.
Another object of the present invention is to provide an air sac for use on a low air loss bed capable of rolling a patient back and forth on the bed while safely retaining the patient thereon.
Other objects and advantages will be apparent to those of skill in the art from the following disclosure.